javascript - How can I find when HTML5 audio actually starts playing (onplay event does not seem to work anywhere) -

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i need catch exact moment when html5 audio starts producing sound.

it turns out not simple seems.

you might expect audio starts playing when onplay or onplaying event fired? no way. @ least in webkit family, seems no browser event fires @ point of time. in chrome, safari , firefox onplay , onplaying events faking behaviour firing oncanplay!

i've prepared simple test prove fact. demonstrates audio starts playing after reasonable time (over 100ms - 400ms) when events had been fired.

you can notice ears , ears if @ console log. in log output currenttime every 15ms. seems reflect actual audio state correctly, , starts changing 10-40 polls after event has been fired. audio still freezed after play fired.

test code looks this:

    var audioel = new audio('http://www.w3schools.com/tags/horse.ogg');      audioel.oncanplay = function () {         console.log('oncanplay');          audioel.currenttime = 1;              console.log('ready state is: ' + audioel.readystate);         audioel.play();     }       audioel.oncanplay = function () {         console.log('oncanplay again');     }      audioel.onplay = function() {         console.log('onplay -----------------');     }      audioel.onplaying = function() {         console.log('onplaying ----------------');     }      setinterval(function () {         console.log(audioel.currenttime);     }, 15);

jsfiddle

i critically need know exact moment when audio starts playing precise synchronisation visual animations.

of course, can find moment using quick polling. bad performance in real-time app, on mobile.

i'm asking if knows better solution this. html audio implementation looks still poor in 2014 :(

as @justin says, can listen playing event (more or less) precise moment media starts playing. yeah i've been seeing spotty support media events , readystate in general, even in latest chrome.

whether events work or not, advise against using setinterval animation (or else, matter). instead, use requestanimationframe, fire more , should synchronize browser , video card's repaint. , can poll currenttime value on every frame calculate should in animation. performance shouldn't problem; case exactly requestanimationframe designed for.

function update() {     var currenttime = audioel.currenttime;     // update animation here     requestanimationframe(update); }  update();

while you're @ it, don't set currenttime 5 until after readystate > 0 or loadedmetadata event fires. if try set currenttime before browser has loaded enough of video file know duration, throw error. can call play() whenever want; doesn't have wait canplay.


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